The word rusticle is a portmanteau of the words rust and icicle and was coined by Robert Ballard, who first observed them on the wreck of the Titanic in 1986.[3] Rusticles on the Titanic were the first investigated in 1996 by Roy Cullimore, based at the University of Regina in Canada. A new species of bacteria living inside the Titanic's rusticles called Halomonas titanicae was discovered in 2010. Henrietta Mann, the scientist who discovered the bacteria, has estimated that the Titanic may collapse circa 2030.[4]

Rusticles can form on any submerged steel object and have been seen on other subsea structures such as mooring chains[5] and subsea equipment. They form more rapidly in warmer climates and can form in water with little to no dissolved oxygen.[5]

Structurally, rusticles contain channels to allow water to flow through, and they seem to be built up in a ring structure similar to the growth rings of a tree. They are very delicate and can easily disintegrate into fine powder on even the slightest touch.